[R-sig-Geo] How to overlay dahed contours on to filled contours?

[Benjamin Laken]

Hi everyone,
I have two seperate netcdf files with 2D data (of dims 72x7), and I need 
one to be a standard filled contour, however I need the other to be 
overlaid on top of the initial filled contour as contour lines.
Any ideas on how I can do this?
(Or at least how I can make a plot with the contours as lines so i can 
cheat and overlay them in adobe illustrator?)

Thanks
--Ben